<!DOCTYPE html>
<html>
	<head>
		<meta charset="UTF-8">
		<title></title>
	</head>
	<body>
		
		<script>
			"use strict"
			
			console.log(0 == -0)
			console.log(NaN == NaN)
			console.log(Object.is(0, -0))
			console.log(Object.is(NaN, NaN))
			
			let obj = {}
			let obj1 = {username: "kobe", age: 12}
			let obj2 = {sex: "男"}
			Object.assign(obj, obj1, obj2)
			console.log(obj)
			
			let obj3 = {}
			let obj4 = {qian: 5000000}
			obj3.__proto__ = obj4
			console.log(obj3)
			console.log(obj3.qian)
		</script>
	</body>
</html>
